feat: support customize flexsearch tokenize option (#319)

Co-authored-by: loenvom <loenvom@qq.com>

exampleSite/hugo.yaml

@@ -136,6 +136,9 @@ params:
     flexsearch:
       # index page by: content | summary | heading | title
       index: content
+      # full | forward | reverse | strict 
+      # https://github.com/nextapps-de/flexsearch/#tokenizer-prefix-search
+      tokenize: forward
 
   editURL:
     enable: true